This invention concerns a method for separating the components of a non-Newtonian fluid.
The filtration of small particles in suspension in stationary and flowing fluids is required in many industries. Using conventional techniques of passing the fluid through a fine mesh leads to early clogging of this mesh. Other techniques use centrifugal separation which gives a good non-clogging effect but requires a considerable energy source and a large pressure drop.
An example of current filtration use is in the paper industry, where fresh wood pulp is added to the water after the production of each batch of paper. The water contains special clay, glycol and some sulphur, which makes it rather expensive. Wood pulp, however, contains a lot of dust that has substantially the same density as the water and therefore stays in suspension. The amount of dust increases with each successive use of the water, resulting in the progressive reduction of the quality of the paper produced. Eventually the level of dust becomes so high that the old water cannot be used any more, and a fresh mixture of water-clay-glycol has to be made. The old mixture is left in tanks, and some crude attempts at filtering it are made. Perhaps 30% of the dust is removed, and this enables a re-run of some cheap paper production. In the end, however, the water has to be dumped in the river, to the complaints of the river authorities, and at a high cost to the manufacturer, who then has to purchase fresh water, clay and glycol.
The conventional method of skimming the water in the tank is by blowing air through the tank. The dust collects near the bubbles formed and is scooped from the top of the tank. This method, however, is most inefficient, and also expensive, as it requires large compressors to blow the air through the water.
Clearly, a cheaper, more effective method is required, both from the environmental point of view and for sheer economic reasons.
Similar problems are found in power stations drawing their water from the sea. Mesh filters get clogged very rapidly with seaweed, fish and organic growth. Here again, therefore, an improved filtration method is badly needed.
A further major modern problem to which the present invention is applicable is the recovery of oil from an oil slick. Existing methods are expensive, laborious, and succeed in recovering only some of the oil which has been spilled into the sea.